A review of the current status of research on convection-heated in situ extraction of unconventional oil and gas resources (oil shale)

The decline of crude oil reserves and the increase in global energy demand have promoted the research progress of unconventional oil and gas resources (oil shale). Convection heating in-situ mining technology is a new type of oil shale mining technology. This technology can improve the fracture gap connectivity, crude oil fluidity, and heat transfer efficiency in oil shale reservoirs. This technology has become a research hotspot in the field of in-situ mining technology. However, this technology still faces technical problems, such as low heating efficiency and high equipment cost. Therefore, scholars have carried out a lot of improvement research on heat conduction, oil shale structure change, and fluid flow after convection heating oil shale. This review compares and summarizes the technology of in-situ mining oil shale by convection heating, including fracture development, temperature distribution, and fluid migration law in oil shale reservoirs. In addition, the author also introduces the development process, optimization scheme, engineering application, and theoretical guidance of the technology. Finally, the key problems and future development direction of convective heating oil shale technology are prospected.